Interior Secretary Francisco Labastida on Friday joined three other candidates openly running for the governing party's nomination for the July 2000 election.

Their public campaign for the nomination is shattering the backroom politics of the Institutional Revolutionary Party, or PRI, which has run Mexico since 1929. Traditionally, the president effectively picked his successor in office by naming the party's candidate.

Journalists asked Labastida if he intended to run during a press conference in the northwestern city Culiacan. "Of course. That question doesn't even have to be asked," he replied. "I confess it without room for doubt."

Labastida has had strong showings in recent polls. His post as interior secretary, which supervises national security and federal law enforcement, often has been a stepping stone for the presidency. Under PRI tradition, a would-be candidate denies all presidential ambitions in public while trying behind closed doors to curry favor with the current president.

This time, however, three candidates are already openly campaigning after President Ernesto Zedillo insisted he would not impose a candidate and suggested a national primary to choose the party's nominee.

The three previously declared candidates have accused Zedillo's allies of trying to control the nomination process and of undermining the proposed open primary.